Was completely undocumented before. Just needed different tagging so it
could be picked up.
No attempt at this stage of sharing more code between the cmu modules.
gpio_common was built, but wasn't picked up by any documentation.
Use the peripheral_apis style from stm32, but try out the #pragma once
style. Downside is you don't get warnings if you include an sub layer
.h file. Upsides are
* no ifdef/endif blocks
* no /**@cond*/ /**@endcond*/ blocks
* that's enough win!
Somewhat replaces some earlier work done by hg/lg, but much more
complete, so we kept it as is, because it's bringing in even more parts
after this.
Reviewed-by: Karl Palsson <karlp@tweak.net.au>
